1. Technical Field
The disclosure relates to a video processing method and a device thereof, and more particularly to a video processing method and a device thereof applied when motions of video objects are rough.
2. Related Art
Video images have various frequencies, for example, a specification for a film is 24 Hz (that is to say, the film is shot or played in a rate of 24 frames per second), the National Television Standard Committee (NTSC) specification is 60 Hz, and the Phase Alternating Line (PAL) specification is 50 Hz. Therefore, when image data having different frequencies are played on various playing devices, for example, a TV set or a Digital Video Disc (DVD) player, the image data must be converted to a matching playing specification through video processing.
The motion-estimation-motion-compensation (MEMC) is a typical video processing mode, in which the image data at a certain frequency is converted to the image data at another frequency through interpolation and then is displayed. Thus, when a frame is changed, a distance of a motion of an object becomes short, thereby solving the problem of image signal lag and doubling. The MEMC is an intuitive solution, but must be achieved by costing a large amount of software/hardware resources. Further, the algorithm is too complicated, so distinct error images are easily generated due to misjudgment of the object motion during the algorithm process.
Therefore, a video processing method, which does not have the high requirements for software and hardware and has a simpler algorithm, is also available, that is, 3:2 pull down. According to this method, an original 24 Hz image data may be converted to a 60 Hz image data satisfying the NTSC specification. For example, the original frames are {A, B, C, D}, after a 3:2 pull down process, the frames are changed to {A, A, A, B, B, C, C, C, D, D}, so it is known that a proportion between amounts of the converted frames is 3:2. In the converted image data, some frames are repeated for 3 times and some frames are repeated for twice, so the moving objects in the frames move at different speeds, resulting in a feeling of rough motions.
Therefore, in Taiwan, R.O.C Patent Application No. 94127529, entitled “Video Processing Method Capable of Preventing Rough Movement of Video Object and Related Device” (the patent is granted, and the patent number is 1268708), the proportion between the amounts of the converted frames is changed from 3:2 to 3:3 (when an output frequency is 72 Hz) or 2:2 (when the output frequency is 48 Hz), so as to solve the problem of the rough motion of the image. However, in the patent, a video signal must be read according to a first refresh frequency, and the adjusted video signal is output according to a second refresh frequency. That is to say, in the patent, a timing control action must be executed, so circuits related to the timing control must be added, thereby causing an additional cost. In addition, for a liquid crystal display (LCD), sometimes the timing control results in a panel compatibility problem, and some panels even do not allow changes to display timing.
Therefore, the problems resulting from the video image processing need to be solved urgently.